Tuesday, June 02, 2009

TechTeach, Issue Thirteen

I tend to think of my computer like an office. The Central Processing Unit (CPU) is like the person behind the desk giving out instructions on what to do. It handles all the requests for data and controls the devices connected to your computer. You might see the terms: Pentium 4, Duron, Athlon X2, Phenom X3 and X4, Core2Duo, or Celeron, or others in connection with the CPU. Pretty much they all do the same thing. Just some are quicker than others about it. If you are looking for a new computer, the names to look for are Core2 Duo and Athlon X2. The Core2Duo is a better CPU all around, though the Athlon X2 is usually less expensive. The “core” is the part of the CPU does all the work; some CPUs have more than one core to share the work. The most you can get in a desktop computer is four cores, with the Phenom X4 and Core2Quad (and upcoming Core i7) based computers. For casual computer use, there’s not a need for more than two cores yet. Not many programs take advantage of them fully.

Random Access Memory (RAM) is like the desk itself. RAM holds programs that are currently open. And like a desk, the RAM can only hold so much before your computer slows. When your computer runs out of RAM to use, it will start to use the hard drive to store information it’s using. If you currently have a computer with less than 1 gigabyte of RAM installed, you might think about upgrading to at least 1 gigabyte (1GB). 512 megabytes is fine for XP, though if you are starting to run more programs, you might think about an upgrade to 1GB. Vista really does need 2GB to run well. XP Home and Professional do well with 1GB.

The Hard Drive is the file cabinet where all your programs and files are stored. If you look at a picture of the insides, it looks like a record player. There are metal platters that spin with an armature just over the surface. The arm has a small magnet that reads the + and – polarities of the surface. These equal 0’s and 1’s and can be formed into useful information by the CPU which then turns into what you see on the screen. Yes, for all the stuff your computer does, it only uses two numbers. They are measured in gigabytes, and an average hard drive is about 200GBs in size.

The Compact Disk or Digital Versatile Disk are optical devices that require the use of lasers to read the pits and flats, similar to the 0’s and 1’s of a hard drive. A CD can hold either 650MB or 700MB of data and come in recordable (use once) versions, and re-writable (use over) versions. Re-writable CDs (CDrw) have to be formatted before using, but can be used over, as the CD drive can melt the material of the disk. Recordable CDs (CDr) can be used right out of the spindle.

DVDs come in many formats. Not only are they DVDr and DVDrw, but they come in + (plus) and – (minus) versions.And they come in single and dual layers. You can read the front plate of your DVD drive to see what formats is capable of reading and writing to, or see your owner’s manual. DVDs can store up to 4.7GB (4700MB) of data on a single layer and 9.4GB on a dual layer.

A DVD drive can read CDs, but a CD drive cannot read DVDs.

The video card is what displays the data on the screen. They come in two types: onboard and add-in card. For general computer use (word processing, web browsing, email), onboard video is fine. If you plan on gaming, 3D programs, and hypersonic jetfighter studies, then you need an add-in card. Add-in cards also have the advantage of using their own RAM, while onboard video uses system RAM. That’s why if you check the RAM in XP, it will show less than you actually have sometimes.

All computers have sound cards these days. Back in the “old days” of computing, and IBM computer was hard pressed to make beeps. Now, you can get 5.1 and 7.1 sound from an onboard sound chip. Unless you need excellent sound quality, onboard sound is fine.

Floppy drives really aren’t used much any more. You’ll find them on older machines, but with computers booting from optical drives now, you won’t find a new computer with a floppy drive unless you order it that way. Memory card readers are becoming more common now. They can read a variety of memory cards and are treated just like any other drive.

USB stands for Universal Serial Bus. It replaces the serial and parallel ports for devices on the back of your computer. If you have a new printer or scanner, you’ve seen this plug. It’s a narrow rectangle at the computer end, usually on the back. You might find one or two USB ports on the front of your computer. They also have two main plugs at the other end. One is generally used printers, scanners and other larger devices. It looks like little five-sided house. Another is very small, about a quarter inch long and that one is mostly used for cameras and other devices where space is a priority. There are others that are proprietary to the device, such Apple’s iPods.

Serial and parallel ports are now what is called “legacy” and are slowly being removed from computer.

Firewire is not very common, and used for video devices where high-speed data transfers are important. Even Apple is dropping this port from their computers. It’s shaped like a rectangle, with two beveled corners on the right side.

Network cards allow you to connect to routers, high-speed Internet and other computers. They come onboard, as add-in cards and wireless. Most new laptops have built-in wireless networking, so you’d want to purchase a wireless router to take advantage of that.

The thing that connects all these devices together is the motherboard. It has a socket for the CPU, slots for the RAM and add-in cards, and connections on the back plane for keyboards, mice, USB ports, network cables, audio, and other devices. Many of the other devices above can be replaced and you get a working computer back again. If the motherboard fails, it’s probably time to get a new computer.

To get a listing of all the “stuff’ in your computer, download Belarc Advisor.


It’s totally free for personal use, and runs on all versions of Windows from Windows 95 to Windows Vista, but only gives Center for Internet Security ratings on Windows 2000, Windows XP Professional and Windows 2003 versions. If you have been doing the Windows Updates, this isn’t a big concern.

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